The invention arose from the need to develop a power amplifier capable of driving a reactive transducer broadband with up to 600 volt-amperes, which had to be small enough to fit into a 5-inch cylinder. It also had to be lightweight.
In the prior art, power amplifiers to drive transducers at this level are usually large and heavy. They normally require resonating inductors that are also heavy.
600 VOLT-AMPERES WERE REQUIRED OUT OF THE DRIVER. No one transistor was adequate. A hybrid circuit that had short and open circuit protection is used. The transistors reduced out-put with heat and this means they must be derated for reactive loads. For the load required, eight in parallel were used.
No technique was available for paralleling so many units, usefully. A technique devised and believed novel was to have each transistor drive the primary of a transformer. The power addition thus takes place magnetically, in the transformer.